1. Field of the Invention
The present invention relates to an apparatus for preventing oil from draining and, more particularly, to an apparatus for preventing oil from draining in an engine having a Hydraulic Lash Adjuster (HLA), in which oil supplied to various parts of a cylinder head including the HLA does not drain back to a main gallery when the engine is stopped and thus can be reliably supplied to the engine when the engine is restarted.
2. Description of Related Art
An automotive engine includes sliding parts such as a cylinder and a piston and rotating parts such as a crankshaft and a camshaft. These operating parts generate frictional heat through direct contact between metal members, such that roughened frictional surfaces will prematurely wear and, in severe cases, be bonded with each other due to the frictional heat. These problems cause severe trouble to the operation of the engine.
In order to prevent such problems, the automotive engine is equipped with a lubrication system. The lubrication system injects oil into various parts of the engine, which come into direct contact with each other, to thereby form an oil film thereon. The oil film can reduce wear and temperature rise by decreasing frictional resistance.
FIG. 1 is a schematic block diagram illustrating oil passages of a conventional engine lubrication system, and FIG. 2 is a perspective view illustrating conventional oil passages for supplying oil to Hydraulic Lash Adjusters (HLAs) and a cam shaft.
As shown in FIGS. 1 and 2, in the engine lubrication system, an oil pump 2 is provided to force oil from an oil pan 1 to various engine parts to be lubricated, and an oil filter 3 is provided on an oil supply line to filter impurities from oil, which is forced by the oil pump 2.
Oil is forced by the oil pump 2 into an oil gallery or main gallery 4 of a cylinder block, in which oil will lubricate bearing parts of a crankshaft and connecting rods. Then, oil is also supplied from the main gallery 4 to a cylinder head 11 via a non-return valve 10, which is also referred to as a check valve.
From the cylinder head 11, oil is supplied to HLAs 20 and Continuously Variable Valve Timing (CVVT) systems as well as camshaft bearings.
However, when an automobile having the engine provided with the HLAs as described above is not run for a long time, oil supplied to various parts of the cylinder head including the HLAs returns to the main gallery. Then, oil will not be instantaneously supplied to the HLAs and other parts of the cylinder head when the engine is restarted. This causes problems such as heavy noise, premature wear and damage to the engine.
Of course, as shown in FIG. 1, a non-return valve can be installed to prevent oil from returning to the main gallery from the cylinder head when the engine is stopped. In this case, however, an additional valve has to be installed on an oil supply circuit. Furthermore, when the engine is run for a long time, the non-return valve may not operate properly due to sticking.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.